An ultrasound system has become an important and popular diagnostic tool since it has a wide range of applications. Specifically, due to its non-invasive and non-destructive nature, the ultrasound system has been extensively used in the medical profession. Modern high-performance ultrasound systems and techniques are commonly used to produce two-dimensional or three-dimensional ultrasound images of internal features of a target object (e.g., human organs).
The ultrasound system may provide ultrasound images of various modes including a brightness mode (B mode) image representing reflection coefficients of the ultrasound signals reflected from a target object of a living body with a 2D (two-dimensional) image, a Doppler mode (D mode) image representing speed of a moving target object with spectral Doppler by using a Doppler effect, a color Doppler mode (C mode) image representing speed of a moving target object with colors by using the Doppler effect, and an elastic mode (E mode) image representing mechanical characteristics of tissues object before and after applying a pressure thereto. Particularly, the ultrasound system may transmit and receive ultrasound signals to and from the living body to thereby form Doppler signals corresponding to a sample volume, which is set on a B mode image. The ultrasound system may further form the D mode image (i.e., Doppler spectrum image) that represents the speed of the moving target object such as blood flow, heart, etc. with Doppler spectrums based on the Doppler signals.
The ultrasound system may provide the Doppler spectrum image only based on the blood flow information. Thus, it is required to provide additional information corresponding to a change of the blood flow with a time to enhance the convenience of a user.